1. Field of the Invention
This invention relates generally to apparatus for aiding in the storing and preserving of donor corneas, and pertains more particularly to improved apparatus for optimumly clamping the sclera in a manner such that the cornea will not be damaged, either by the flow of fluid through the sclera into the corneal stroma or by any physical contact with the delicate endothelium overlying the posterior surface of the cornea.
2. Description of the Prior Art
Inasmuch as corneal transplants are now quite common, the need to preserve corneas from the time they are made available to the time that the transplant takes place has become of prime importance. To preserve the cornea, an organ culture media is made use of, such a media constituting a fluid with certain nutrients, trace metals and antibiotics included therein which will assist in the preservation of the cornea inasmuch as the cornea cells should be sufficiently nourished in order to assure their survival outside of the human body.
One device intended for use in helping to maintain a cornea in condition for subsequent transplanting is described in U.S. Pat. No. 2,929,603, granted on Mar. 22, 1960 to Gene A. Stewart for "CORNEAL CLAMP". The clamp described in said patent utilizes an underlying mounting plate on which a substantially hemispherical form is placed over which the cornea is positioned. The clamp includes in addition to the lower or mounting plate a second or upper plate having an opening therein of a size such that the cornea projects upwardly with respect thereto. The outer periphery of the upper plate is twistably engageable with the mounting plate.
Inasmuch as the underside of the cornea, this being the posterior side that has thereon the endothelium, is extremely sensitive to touch and contact with virtually any object causes it to die immediately. Consequently, any underlying form beneath the endothelium should be avoided. Furthermore, if the clamping pressure is not uniform with respect to the sclera surrounding the cornea, the endothelium continually pumps fluid out of the corneal stroma in an effort to keep the cornea thin but if the sclera is not compressed sufficiently, the fluid simply goes back into the corneal stroma through the relatively porous sclera. Stated somewhat differently, without uniform and complete compression of the sclera, the corneal stroma becomes thicker, and is therefore difficult to assess as far as its viability as a transplant, as well as becoming more difficult to surgically transplant. The undesired physical contact with the endothelium and the fluid flow through the sclera constitute two shortcomings of the clamp described in said Stewart patent.
Virtually the same inadequacies are present in the corneal transplant holder described in Russian Pat. No. 245,988 issued on Nov. 11, 1969. In this instance, transparent hemispherical elements or forms are utilized having flanges which are made of magnetized metal so that the hemispheres or forms can be held together by magnetic attraction. Not only is a surface involved that can adversely affect the endothelium, but the magnetic action is not sufficient to crush the porous sclera to the degree that fluid is precluded from flowing therethrough into the corneal stroma.